Multi-cycle ald process for film uniformity and thickness profile modulation

ABSTRACT

Methods of depositing uniform films on substrates using multi-cyclic atomic layer deposition techniques are described. Methods involve varying one or more parameter values from cycle to cycle to tailor the deposition profile. For example, some methods involve repeating a first ALD cycle using a first carrier gas flow rate during precursor exposure and a second ALD cycle using a second carrier gas flow rate during precursor exposure. Some methods involve repeating a first ALD cycle using a first duration of precursor exposure and a second ALD cycle using a second duration of precursor exposure.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. Provisional Patent ApplicationNo. 62/190,618 filed Jul. 9, 2015, and titled “MULTI-CYCLE ALD PROCESSFOR FILM UNIFORMITY AND THICKNESS PROFILE MODULATION,” which isincorporated by reference herein in its entirety and for all purposes.

BACKGROUND

Various thin film layers for semiconductor devices may be deposited withatomic layer deposition (ALD) processes. However, existing ALD processesmay not be suitable for depositing highly conformal dielectric films.For example, many existing ALD processes cannot offer a combination ofhigh throughput (rapid deposition) and high conformality.

SUMMARY

Provided herein are methods of processing substrates. One aspectinvolves a method of processing a substrate housed in a chamber by (a)exposing the substrate to a reactant for a duration insufficient tosaturate the surface of the substrate; (b) exposing the substrate to aplasma to deposit at least a partial layer of film on the substrate; and(c) repeating (a) and (b) in two or more deposition cycles, wherebyvalues of one or more parameters during at least one of (a) or (b) arevaried during the two or more deposition cycles.

In various embodiments, one of the one or more parameters is theduration of (a). In various embodiments, one of the one or moreparameters is a duration of (b). In some embodiments, the duration of(a) is greater than a duration of (b). In some embodiments, the durationof (a) is between about 0.05 second and about 5 seconds. In someembodiments, the duration of (a) is between about 0.1 second and about 1second. In some embodiments, the duration of (b) is between about 0.05second and about 5 seconds.

In some embodiments, one of the one or more parameters is carrier gasflow rate during (a). In some embodiments, one of the one or moreparameters is process gas flow rate during (b). In some embodiments, thecarrier gas flow rate during (a) may be between about 0.5 slm (standardliters per min) and about 20 slm. In some embodiments, the process gasflow rate during (b) may be between about 0.5 slm and about 20 slm.

In various embodiments, one of the one or more parameters is plasmapower during (b). In some embodiments, the plasma power can be betweenabout 50 W and about 6000 W.

In some embodiments, one of the one or more parameters is composition ofthe reactant in (a). In some embodiments, one of the one or moreparameters is composition of carrier gases flowed during (a). In someembodiments, one of the one or more parameters is composition of processgases flowed during (b).

In some embodiments, exposing the substrate to the plasma in (b) furtherincludes exposing the substrate to a second reactant. In someembodiments, one of the one or more parameters is composition of thesecond reactant.

The method may further include (d) purging the chamber after at leastone of (a) or (b) one or more of the two or more deposition cycles. Insome embodiments, purging the chamber includes flowing a purge gas. Oneof the one or more parameters may be duration of (d). In someembodiments, one of the one or more parameters is composition of thepurge gas in (d).

Another aspect involves a method of processing a substrate housed in achamber, the method including depositing a film by repeating two or moredeposition cycles, whereby a deposition cycle includes: (a) exposing thesubstrate to a reactant, and (b) exposing the substrate to a plasma todeposit the film, whereby values of one or more parameters during one of(a) or (b) are varied from cycle to cycle in a process cycle.

In some embodiments, one of the one or more parameters is a duration of(a). In some embodiments, one of the one or more parameters is aduration of (b). In some embodiments, the duration of (a) is greaterthan a duration of (b). The duration of (a) may be between about 0.1second and about 1 second. In some embodiments, the duration of (b) isbetween about 0.05 second and about 5 seconds.

In some embodiments, one of the one or more parameters is carrier gasflow rate during (a). In some embodiments, one of the one or moreparameters is process gas flow rate during (b). In some embodiments, thecarrier gas flow rate during (a) may be between about 0.5 slm (standardliters per min) and about 20 slm. In some embodiments, the process gasflow rate during (b) may be between about 0.5 slm and about 20 slm. Invarious embodiments, one of the one or more parameters is plasma powerduring (b). In some embodiments, the plasma power can be between about50 W and about 6000 W. In some embodiments, one of the one or moreparameters is composition of the reactant in (a).

The deposition cycle may further include (c) purging the chamber afterat least one of (a) or (b) in one or more of the two or more depositioncycles. In some embodiments, purging the chamber includes flowing apurge gas. In some embodiments, one of the one or more parameters isduration of (c). In various embodiments, one of the one or moreparameters is composition of the purge gas in (c).

In some embodiments, one of the one or more parameters is composition ofcarrier gases flowed during (a). In some embodiments, one of the one ormore parameters is composition of process gases flowed during (b).

In some embodiments, exposing the substrate to the plasma furtherincludes exposing the substrate to a second reactant. In someembodiments, the one or more parameters is composition of the secondreactant.

Another aspect involves an apparatus for processing semiconductorsubstrates, the apparatus including: a. at least one process chamberincluding a pedestal for holding a substrate; b. at least one outlet forcoupling to a vacuum; c. one or more process gas inlets coupled to oneor more precursor sources; d. one or more process gas inlets coupled toone or more second reactant sources; and e. a controller for controllingoperations in the apparatus, including machine readable instructionsfor: i. introducing one of the one or more precursor sources to theprocess chamber for a duration insufficient to saturate the surface ofthe substrate; ii. igniting a plasma to deposit at least a partial layerof film on the substrate; and iii. repeating (i) and (ii) in two or moredeposition cycles and varying one or more parameter values during atleast one of (i) or (ii) during the two or more deposition cycles.

In some embodiments, the machine readable instructions further includepurging the at least one process chamber after introducing the one ofthe one or more precursor sources. In some embodiments, the machinereadable instructions further include purging the at least one processchamber after igniting the plasma. In some embodiments, the plasma powercan be between about 50 W and about 6000 W.

Another aspect involves an apparatus for processing semiconductorsubstrates, the apparatus including: a. at least one process chamberincluding a pedestal for holding a substrate; b. at least one outlet forcoupling to a vacuum; c. one or more process gas inlets coupled to oneor more precursor sources; d. one or more process gas inlets coupled toone or more second reactant sources; and e. a controller for controllingoperations in the apparatus, including machine readable instructionsfor: i. introducing one of the one or more precursor sources to theprocess chamber with a carrier gas at a first carrier gas flow rate; ii.igniting a plasma to deposit a film; and iii. varying one or moreparameter values during one of (i) or (ii) from cycle to cycle in aprocess cycle.

In some embodiments, the machine readable instructions further includepurging the at least one process chamber after introducing the one ofthe one or more precursor sources. In some embodiments, the machinereadable instructions further include purging the at least one processchamber after igniting the plasma. In some embodiments, the plasma powercan be between about 50 W and about 6000 W.

These and other aspects are described further below with reference tothe drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a substrate process station illustratingprecursor flow within a processing chamber during a deposition process.

FIG. 2A is a schematic representation of a configuration of a multi-stepprecursor delivery system for a substrate process station.

FIG. 2B is a schematic representation of another configuration of amulti-step precursor delivery system for a substrate process station.

FIG. 2C is a schematic representation of an additional alternativeconfiguration of a multi-step precursor delivery system for a substrateprocess station.

FIG. 3 is a process flow diagram depicting operations for a method inaccordance with disclosed embodiments.

FIG. 4A is a process flow diagram depicting operations for an example ofa method in accordance with disclosed embodiments.

FIG. 4B is a timing sequence diagram showing an example of cycles in amethod in accordance with disclosed embodiments.

FIG. 5A is a process flow diagram depicting operations for an example ofa method in accordance with disclosed embodiments.

FIG. 5B is a timing sequence diagram showing an example of cycles in amethod in accordance with disclosed embodiments.

FIG. 6 is a schematic diagram of an example process station forperforming disclosed embodiments.

FIG. 7 is a schematic diagram of an example process tool for performingdisclosed embodiments.

FIGS. 8A and 11 are graphs depicting pulsing and timing schemescorresponding to processes in experiments performing disclosedembodiments.

FIGS. 8B, 9A, 9B, 10A, 10B, and 12 are graphs depicting thickness ofdeposited films on wafers from experiments performed in accordance withdisclosed embodiments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth toprovide a thorough understanding of the presented embodiments. Thedisclosed embodiments may be practiced without some or all of thesespecific details. In other instances, well-known process operations havenot been described in detail to not unnecessarily obscure the disclosedembodiments. While the disclosed embodiments will be described inconjunction with the specific embodiments, it will be understood that itis not intended to limit the disclosed embodiments.

Semiconductor fabrication processes may involve deposition of variousmaterials using atomic layer deposition (ALD). ALD processes usesurface-mediated deposition reactions to deposit films on alayer-by-layer basis and often involve saturating a surface of asubstrate with a precursor to deposit material in a self-limitingreaction. In one example of an ALD process, a substrate surface,including a population of surface active sites, is exposed to a gasphase distribution of a first reactant or precursor, such as asilicon-containing precursor, in a dose provided to a process stationhousing the substrate. Molecules of this first precursor are adsorbedonto the substrate surface, including chemisorbed species and/orphysisorbed molecules of the first precursor. It should be understoodthat when the compound is adsorbed onto the substrate surface asdescribed herein, the adsorbed layer may include the compound as well asderivatives of the compound. For example, an adsorbed layer of asilicon-containing precursor may include the silicon-containingprecursor as well as derivatives of the silicon-containing precursor.After a first precursor dose, the reactor is then evacuated to removeany first precursor remaining in gas phase so that only the adsorbedspecies remain. A second reactant is introduced to the reactor so thatsome of these molecules react with the first precursor adsorbed on thesurface. In some processes, the second precursor reacts immediately withthe adsorbed first precursor. In other embodiments, the second precursorreacts only after a source of activation is applied temporally. Thereactor may then be evacuated again to remove unbound second precursormolecules and reaction by-products. Additional ALD cycles may be used tobuild film thickness. In some embodiments, only a single reactant isused and a thermal or plasma operation is used to convert adsorbedprecursor to a desired deposition material.

In certain embodiments, an ALD precursor dose partially saturates thesubstrate surface. ALD processes performed in a sub-saturated regime maybe referred to as sub-saturated ALD (“SS-ALD”). Films deposited bySS-ALD methods may have the following features: (1) throughput isimproved by substantially reducing the precursor dose time in eachcycle, (2) film thickness may be precisely modulated by depositing verythin sub-saturated layers per deposition cycle, in some cases the percycle thickness being less than the largest bond length of the desiredfilm; (3) in the aggregate, continuous thin films may be deposited; (4)deposited films may have improved properties, such as improved wet etchrate control; and (5) reduced precursor consumption since the surface isnot entirely saturated by adsorbed molecules. Undersaturation may becontrolled by limiting the flow or dose of reactive species to thesurface.

In some embodiments, the dose phase of an ALD cycle concludes before theprecursor evenly saturates the surface of the substrate. Typically, theprecursor flow is turned off or diverted at this point, and only purgegas flows. By operating in this subsaturation regime, the ALD processreduces the cycle time and increases throughput. However, becauseprecursor adsorption is not saturation limited, the adsorbed precursorconcentration may vary slightly across the substrate surface. Examplesof ALD processes operating in the sub-saturation regime are provided inU.S. patent application Ser. No. 14/061,587, filed Oct. 23, 2013, titled“SUBSATURATED ATOMIC LAYER DEPOSITION AND CONFORMAL FILM DEPOSITION,”which is incorporated herein by reference in its entirety.

ALD and SS-ALD processes currently use the same process conditions fromcycle to cycle, but in some SS-ALD processes the deposition may not beuniform. ALD, particularly sub-saturated ALD, is sensitive to type ofshowerhead and delivery method and flow, as well as partial pressure ofprecursor. Multiple ALD cycles may be repeated to build up stacks ofconformal layers. In some implementations, each layer may havesubstantially the same composition whereas in other implementations,sequentially ALD deposited layers may have differing compositions, or incertain such implementations, the composition may alternate from layerto layer or there may be a repeating sequence of layers having differentcompositions, as described above.

Various types of hardware may be used. Examples are provided in U.S.patent application Ser. No. 14/578,166, filed on Dec. 19, 2014 entitled“HARDWARE AND PROCESS FOR FILM UNIFORMITY IMPROVEMENT,” which is hereinincorporated by reference in its entirety. FIG. 1 provides a schematicof a substrate process station illustrating precursor flow within aprocessing chamber during a deposition process. The substrate processstation 100 includes a showerhead 102 and a pedestal 104 supporting asubstrate 106.

Process gas 108 is delivered to the substrate 106 via the showerhead102. In certain implementations, the process gas 108 may be a precursoror a combination of precursor and carrier gas. The substrate may adsorbthe precursor and form an adsorption layer on the substrate 106. Duringcertain phases of a deposition cycle, a purge gas or other process gasesmay flow via the showerhead 102 instead of the process gas 108.

Additionally, in FIG. 1, a purge gas 110 may flow along the exterior ofthe showerhead 102. In certain implementations, the purge gas 110 mayprevent deposition on the backside of the showerhead 102.

The flow of the process gas 108 and the purge gas 110 around theinterior of the substrate process station 100 may result in unevendosing of the substrate 106. Uneven dosing may result in non-uniformprocessed substrates. In certain implementations, the flow of theprocess gas 108 over the surface of the substrate 106 may result inuneven dosing of area 112 on the surface of the substrate 106.Additionally, the flow of purge gas 110 may result in uneven dosing ofareas 114A and 114B on the surface of the substrate 106. The results ofuneven dosing in some implementations may result in non-uniformdeposition.

The process gas 108 in FIG. 1 may be delivered through a process gasdelivery system in a substrate processing apparatus. A process gasdelivery system may include a configuration of flow paths and valves.Valves which may be used in precursor gas delivery systems includepneumatically and electrically actuated diaphragm-sealed orbellow-sealed valves and valve manifolds such as ALD valves, DP seriesvalves from Swagelok, and MEGA series, Standard series and electricallycontrolled valves from Fujikin.

Provided herein are methods of depositing uniform layers usingmulti-cyclic ALD. In multi-cyclic ALD, more than one set of conditionsfor an ALD cycle is included in a “process cycle.” A process cycle isdefined as a unit of operations that are repeated over time. An ALDcycle is defined as the set of operations including at least one doseand one conversion step (e.g., an ALD cycle may bedose/purge/conversion/purge or conversion/purge/dose/purge ordose/conversion, etc.). Multi-cyclic ALD involves repeating processcycles that include more than one ALD cycle. Each ALD cycle in a processcycle may change the value of one or more parameters during any of theoperations in an ALD cycle. In certain embodiments, some parametervalues may not be changeable due to the time it takes to change theparameter value between cycles. For example, mass flow controller (MFC)flows, liquid flow controller (LFC) flows, and pressure may not bechanged between cycles. In some apparatus, the time required to changethe value of one or more of these parameters is on the order of the timerequired to perform a cycle. As a consequence, such parameter valuescannot be realistically adjusted from cycle-to-cycle withoutdramatically reducing throughput. Of course, if an apparatus allowsrapid adjustment, some parameter values may be varied dynamically.

In certain embodiments, one or more of the following parameter valuesare changed between cycles in a multi-cycle process: timing, such asdose time, which is controllable by a divert valve, duration of plasmaexposure, and purge time; and different carrier gas flows, such ascarrier gas flow on/off for flows at different rates and differentcompositions and some combination of carrier gases; and plasma power.The different carrier gas flows may be rapidly adjusted by controllingvalve timing for various manifolds used to deliver the carrier gas(es).

Embodiments herein may involve various types of process gas flow.Precursor delivery systems, which may be referred to as multi-stepprecursor delivery systems, may be implemented with both vapor-baseddelivery systems and liquid delivery systems. Vapor-based deliverysystems may use an ampoule to evaporate precursor. Liquid deliverysystems may use a vaporizer to evaporate precursor. FIG. 2A is aschematic representation of a configuration of a multi-step precursordelivery system for a substrate process station.

The multi-step precursor delivery system 200A in FIG. 2A includes afirst process gas source 202 connected to a first flow path 204 and asecond process gas source 218 connected to a second flow path 220. Incertain implementations, the first process gas from the first processgas source 202 may be a process gas which includes precursor and/orcarrier gas. Additionally, the second process gas from the secondprocess gas source 218 may be a process gas which includes precursorand/or carrier gas. The precursor and/or carrier gas used for the firstand second process gases may be similar or different. The carrier gasmay be a gas such as argon, nitrogen (N₂), oxygen (O₂), nitrous oxide(N₂O), helium, other inert gases, or a mixture of these gases. Incertain other implementations, a carrier gas source may be sharedbetween the first flow path and the second flow path, with a furtherprecursor source connected to the first flow path and/or the second flowpath. In such implementations, the carrier gas and the precursor may bemixed at some point before entering the showerhead. In certainimplementations, single valves in the figures described herein may bereplaced with multiple valves.

The first flow path 204 is fluidically connected to the showerhead flowpath 206 and a first divert flow path 210. The showerhead flow path 206leads to a showerhead 208 while the first divert flow path 210 leads tothe first divert dump 212A. The flow of process gas from the first flowpath 204 into the showerhead flow path 206 is controlled by a firstshowerhead valve 224. The flow of process gas from the first flow path204 into the first divert flow path 210 is controlled by a first divertvalve 226. In certain implementations, only one of the first showerheadvalve 224 and the first divert valve 226 may be open at any one time.Additionally, in certain implementations, the first flow path may bedirectly connected to the showerhead, possibly with a first showerheadvalve controlling the flow of process gas between the first flow pathand the first showerhead. In such implementations, there may not be afirst showerhead flow path.

The second flow path 220 is fluidically connected to the showerhead flowpath 206 and a second divert flow path 222. The second divert flow path222 leads to the second divert dump 212B. The flow of process gas fromthe second flow path 220 into the showerhead flow path 206 is controlledby a second showerhead valve 228. Flow from the second flow path 220into the second divert flow path 222 is controlled by a second divertvalve 230. In certain implementations, only one of the second showerheadvalve 228 and the second divert valve 230 may be open at any one time

In certain implementations, the multi-step precursor delivery system200A may be controlled by a controller as described elsewhere in thisdisclosure. In certain implementations, the multi-step precursordelivery system 200A first delivers process gas from the first processgas source 202 to the showerhead 208 before delivering process gas fromthe second process gas source 218 to the showerhead 208 at a later timeperiod. The delivery periods of the first process gas and second processgas may overlap. The timing of the delivery periods of the first processgas and the second process gas is described in greater detail elsewherein this disclosure.

FIG. 2B is a schematic representation of another configuration of amulti-step precursor delivery system for a substrate process station.The multi-step precursor delivery system 200B is similar inconfiguration to the delivery system 200A. In the multi-step precursordelivery system 200B the first showerhead valve 224 and the first divertvalve 226 is replaced with a first flow path valve 232. In certainimplementations, the first flow path valve 232 may be configured toalternatively direct process gas flow from the first flow path 204towards either the showerhead flow path 206 or the first divert flowpath 210.

Additionally, the second showerhead valve 228 and second divert valve230 of the delivery system 200A in FIG. 2A has been replaced with asecond flow path valve 234 in the multi-step precursor delivery system200B in FIG. 2B. The second flow path valve 234 may be similar inconfiguration to the first flow path valve 232. In certainimplementations, the second flow path valve 234 may alternatively directprocess gas flow from the second flow path 220 towards either theshowerhead flow path 206 or the second divert flow path 222.

FIG. 2C is a schematic representation of an additional alternativeconfiguration of a multi-step precursor delivery system for a substrateprocess station. The multi-step precursor delivery system 200C issimilar in configuration to the delivery system 200A. In the multi-stepprecursor delivery system 200C, the second flow path 220 terminates intoa portion of the first flow path 204. Thus, the first showerhead valve224 may control the flow of both the first process gas and the firstprocess gas to the showerhead 208. Such a configuration may be used whenthe first and second process gases are timed to cease flowing to theshowerhead at the same time. In such cases, the first showerhead valve224 may simultaneously shut off the flow of both process gases.

FIG. 3 provides a process flow diagram depicting multi-cyclic ALD inaccordance with disclosed embodiments. In operation 392, a first ALDcycle is performed. An ALD cycle involves alternating between doses oftwo or more reactants with a purge step in between to remove excessreactant/by-products. In some embodiments, the ALD cycle involvesplasma-enhanced ALD (PEALD) in a saturated or sub-saturated regime.During PEALD, a plasma is ignited during at least one of the doses in anALD cycle. In operation 394, a second ALD cycle is performed. The secondALD cycle may be performed such that one or more parameter values aredifferent from the first ALD cycle performed in operation 392. Examplesof parameter values that may be different between the first and secondALD cycles include dose time, purge time, plasma exposure time, valvetiming for carrier gas flow, and radio frequency (RF) plasma power andfrequency. For example, in operation 394, the dose times during onecycle may be shorter than dose times in another cycle in operation 392.Further examples of varying parameter values between ALD cycles aredescribed below.

In operation 396, the nth ALD cycle may be performed after potentiallynumerous intervening cycles. That is, any two or more ALD cycles may beperformed in accordance with disclosed embodiments, with any one ALDcycle changing one or more parameter values. In various embodiments,each of 1st, 2nd . . . nth ALD cycles may be distinct from one another.For example, each of the n cycles may have different dose times. In someembodiments, only some of the n cycles may have different dose times.The order in which some of the operations are performed may be changedthroughout the process. For example, for a process having threedifferent dose times t₁, t₂, and t₃, the process may be performed in anycombination of operations, including any of the following examples ofcycling such operations:

Example 1 (repeated sequentially): t₁, t₂, t₃, t₁, t₂, t₃, t₁, t₂, t₃,t₁, t₂, t₃ . . . .

Example 2 (random cycles): t₁, t₂, t₃, t₂, t₁, t₁, t₂, t₂, t₃, t₁, t₂,t₂, t₃, t₁ . . . .

Example 3 (varied sequences): t₁, t₂, t₁, t₂, t₃, t₁, t₂, t₁, t₂, t₃,t₁, t₂, t₁, t₂, t₃ . . . .

In disclosed embodiments, n may be any integer greater than or equal to2. In operation 398, operations 392-396 may be repeated. For example, ifn=3, then the first, second, and third ALD cycles may be constitute amulti-cyclic ALD process cycle that is repeated. In various embodiments,an operation whereby one or more parameter value is changed may not beperformed in every multi-cyclic ALD cycle, but may instead be performedafter one of the other operations in a multi-cyclic ALD cycle isperformed, or after performing one of the other operations two times, orthree times, or more. In some embodiments, operations in a multi-cyclicALD cycle may be performed randomly. In some embodiments, operations392-396 may be referred to as one multi-cycle ALD process cycle, or“process cycle” as used herein. Note that a process cycle includes twoor more ALD cycles, each of which may have a distinct set of parametervalues, such as different dose times or different plasma powers, ordifferent carrier gas flows. Disclosed embodiments are suitable fordepositing any material using ALD, such as oxides, nitrides, andcarbides of silicon.

Further examples of multi-cyclic ALD process cycles are provided herein.FIG. 4A shows an example process cycle including two ALD cycles wherethe carrier gas flow is varied from cycle to cycle. FIG. 4A correspondsto example timing schematic diagram FIG. 4B, which provides the variouspulses and flows for each ALD cycle and each multi-cyclic ALD cycle.FIG. 5A shows an example process cycle including two ALD cycles wherethe precursor dose time is varied from cycle to cycle. FIG. 5Acorresponds to example timing schematic diagram FIG. 5B, which providesthe various pulses and flows for each ALD cycle and each multi-cyclicALD cycle. FIGS. 4A and 4B will be discussed together below.

In FIG. 4A, in operation 402 a, a substrate is exposed to a precursor ata first carrier gas flow. The substrate may be a silicon wafer, e.g., a200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers havingone or more layers of material, such as dielectric, conducting, orsemi-conducting material deposited thereon. In various embodiments, thesubstrate is patterned. A patterned substrate may have “features” suchas via or contact holes, which may be characterized by one or more ofnarrow and/or re-entrant openings, constrictions within the feature, andhigh aspect ratios. The feature may be formed in one or more of theabove described layers. One example of a feature is a hole or via in asemiconductor substrate or a layer on the substrate. Another example isa trench in a substrate or layer. In various embodiments, the featuremay have an under-layer, such as a barrier layer or adhesion layer.Non-limiting examples of under-layers include dielectric layers andconducting layers, e.g., silicon oxides, silicon nitrides, siliconcarbides, metal oxides, metal nitrides, metal carbides, and metallayers.

In some embodiments, the feature may have an aspect ratio of at leastabout 1:1, at least about 2:1, at least about 4:1, at least about 6:1,at least about 10:1, or higher. The feature may also have a dimensionnear the opening, e.g., an opening diameter or line width of betweenabout 10 nm to 10 μm, for example between about 25 nm and about 1 μm.Disclosed methods may be performed on substrates with features having anopening less than about 250 nm. A via, trench or other recessed featuremay be referred to as an unfilled feature or a feature. According tovarious embodiments, the feature profile may narrow gradually and/orinclude an overhang at the feature opening. A re-entrant profile is onethat narrows from the bottom, closed end, or interior of the feature tothe feature opening. A re-entrant profile may be generated by asymmetricetching kinetics during patterning and/or the overhang due tonon-conformal film step coverage in the previous film deposition, suchas deposition of a diffusion barrier. In various examples, the featuremay have a width smaller in the opening at the top of the feature thanthe width of the bottom of the feature.

The carrier gas used in operation 402 a may be nitrogen, argon or otherinert gas, oxygen, nitrous oxide, a combination of inert gases or otherprocess gases. The substrate may be exposed to a precursor for aduration sufficient to saturate less than 100% of the substrate surface.Example durations depend on wafer chemistry, type of precursor,precursor flow rate, patterns on the wafer, and other factors. Durationmay be selected depending on the type of substrate profile desired. Insome embodiments, the duration of the precursor exposure may be shorterto adsorb less precursor near the edge of the substrate to form athinner layer near the edge, and a thicker layer in the middle of thesubstrate. In some embodiments, the duration of the precursor exposuremay be longer to adsorb more precursor near the edge of the substrate toform a thicker layer near the edge. In some embodiments, the substratemay be exposed during operation 402 a for a duration less than about 5seconds, or between about 0.05 second and about 3 seconds. Fordeposition of oxides, the dose time may be between about 0.05 secondsand about 0.5 seconds. The substrate is exposed to a precursor or afirst reactant. The precursor may be selected depending on the type ofmaterial to be deposited. For example, to deposit a silicon nitride or asilicon oxide film, a silicon-containing precursor may be used duringoperation 402 a.

In operation 404 a, the chamber is optionally purged to remove excessprecursor in gas phase that did not adsorb onto the surface of thesubstrate. Purging may involve a purge or sweep gas, which may be acarrier gas used in other operations or a different gas. In someembodiments, the purge gas may be nitrogen, argon or other inert gas,oxygen, nitrous oxide, a combination of inert gases, or combinationsthereof. In some embodiments, the purge gas is the same chemistry as thecarrier gas used during precursor doses. In some embodiments, the purgegas is the same gas flowed during a plasma operation as furtherdescribed below. In some embodiments, the purge gas is flowed from thesame gas source from where carrier gas is flowed. In some embodiments,purging may involve evacuating the station. In some embodiments, a purgemay include one or more evacuation purges for evacuating the processstation. In some embodiments, the purge may be performed for anysuitable duration, such as between about 0 seconds and about 60 seconds.In some embodiments, increasing a flow rate of a one or more sweep gasesmay decrease the duration of the purge. For example, a purge gas flowrate may be adjusted according to various reactant thermodynamiccharacteristics and/or geometric characteristics of the process stationand/or process station plumbing for modifying the duration of operation404 a. In one nonlimiting example, the duration of a sweep phase may beadjusted by modulating sweep gas flow rate. This may reduce depositioncycle time, which may improve substrate throughput. After a purge, someprecursor molecules may remain adsorbed onto the substrate surface.

In operation 406 a, the substrate is exposed to a plasma. For example,the substrate may be exposed to a second reactant capable of reactingwith the precursor to form a material on the surface of the substratewhile a plasma is ignited to catalyze the reaction. The second reactantmay be selected depending on the type of film to be deposited. Forexample, for a silicon nitride film, the substrate may be exposed to anitrogen-containing reactant while a plasma is ignited in operation 406a to deposit the silicon nitride film. As another example, for a siliconoxide film, the substrate may be exposed to an oxygen-containingreactant while a plasma is ignited in operation 406 a to deposit asilicon oxide film.

In operation 408 a, the chamber is again optionally purged. The purgeconditions in some embodiments may be the same as the purge conditionsin operation 404 a. In some embodiments, purge conditions may be varied.For purposes of this example, the purge conditions may be the same asthose in operation 404 a.

Operations 402 a-408 a may constitute one ALD cycle of a multi-cycle ALDprocess cycle. In FIG. 4A, another ALD cycle of the multi-cycle ALDprocess cycle is provided in operations 402 b-408 b. However, the secondALD cycle provided in operations 402 b-408 b involve one or moredifferent parameter values than in operations 402 a-408 a. Theoperations 402 b-408 b in FIG. 4A provide one example whereby thecarrier gas flow during precursor exposure is different than the carriergas flow in the first ALD cycle in the process chamber. As shown, inoperation 402 b, the substrate is exposed to a precursor with a secondcarrier gas flow. Compared to operation 402 a, carrier gas flow inoperation 402 b may involve a greater carrier gas flow rate than that ofoperation 402 a, a lower carrier gas flow rate, a different gas flowcomposition, or other variation. For example, an operation for exposingthe substrate to a high carrier gas flow may involve flowing a carriergas at a flow rate of less than about 20 L for a four-station tool, orabout 5 L for a single substrate. An operation for exposing thesubstrate to a low carrier gas flow may involve flowing a carrier gas ata flow rate of less than about 1000 sccm for a four-station tool, orabout 250 sccm for a single substrate.

In some embodiments, a higher carrier gas flow rate may be at leastabout 9 L for one ALD cycle, while the lower carrier gas flow rate maybe about 3 L or less, for an apparatus including four showerheads (e.g.,four stations, each including a pedestal for holding a substrate 300 mmin size). The relative flow rates may depend on the hardware. For somehardware, the relationship between carrier gas flow and type ofresulting profile on the substrate may not be linear. For example, insome embodiments, a high carrier gas flow used in, for example,operation 402 a at about 9 L may result in an edge thick profile, and alow carrier gas flow used in, for example, operation 402 b, at about 3 Lmay result in an edge thin profile, but flowing carrier gas at a flowrate of about 6 L may not result in a uniform deposition profile.

In some embodiments, the substrate may be processed in a chamberincluding two or more manifolds, each of which are capable of flowingcarrier gas. One manifold may also be used to deliver precursor gas. Inoperation 402 a, two manifolds may deliver carrier gas, whereas inoperation 402 b, only one manifold may deliver carrier gas. In someembodiments, the carrier gases in the manifolds may be the same. In someembodiments, the carrier gases in the manifolds may be different.

In operation 404 b, the chamber is optionally purged. In this example,the chamber conditions during purge may be the same as in operation 404a, however it is understood that in some embodiments, purge conditionsmay also be varied from cycle to cycle. In operation 406 b, thesubstrate is exposed to a plasma to form the material to be deposited onthe substrate. In various embodiments, operation 406 b may involve thesame conditions as operation 406 a. Again it is understood that in someembodiments, conditions during operation 406 b may be changed fromcycle-to-cycle and may not necessarily be the same as that of operation406 a. In operation 408 b, the purge is again optionally performed,similar to operation 408 a. Again, here, operation 408 b may notnecessarily involve the same conditions as that of operation 408 a.

Operations 402 a-408 b may then be repeated in cycles to deposit amaterial using this multi-cyclic ALD process. Note that the exampleprovided in FIG. 4A includes two ALD cycles in a multi-cyclic ALDprocess, but in some embodiments, more than two ALD cycles may beincluded such as three cycles, four cycles, five cycles, or more. Forexample, for a three-cycle multi-cyclic ALD process, the carrier gasflow in the first ALD cycle may involve flowing Gas A and Gas B, thecarrier gas flow in the second ALD cycle may involve flowing just Gas Awithout Gas B, and the carrier gas flow in the third ALD cycle mayinvolve flowing just Gas B without Gas A.

FIG. 4B provides a timing schematic diagram showing an example of aprocess 400 where the multi-cyclic ALD cycle in FIG. 4A is repeated.

As shown, the first multi-cyclic ALD cycle 480 includes both the firstALD cycle 410A and 2nd ALD cycle 410B. The process is again repeated inthe second process cycle 490, which includes the first ALD cycle 450Aand second ALD cycle 450B.

The first ALD cycle 410A includes a dose phase 412A, which correspondsto operation 402 a in FIG. 4A. During this operation, both carrier gas 1and carrier gas 2 are flowed, along with the precursor, while the plasmaand second reactant are both turned off. In the purge phase 414A, purgegas is flowed and the plasma is off while the chamber is evacuated. Thisphase corresponds to operation 404 a in FIG. 4A. In RF phase 416A, thesubstrate is exposed to a plasma and the second reactant is flowed toreact with the adsorbed precursor on the surface. This operationcorresponds to operation 406 a. In purge phase 418A, a purge gas isflowed and the plasma is turned off to evacuate the chamber. In thesecond ALD cycle 410B, the dose phase 412B involves flowing only carriergas 2 while carrier gas 1 is turned off, and the precursor is flowed.This corresponds to operation 402 b in FIG. 4A, where a second carriergas is flowed. Compared to the dose phase 412A, only one carrier gas isflowed. In purge phase 414B, which corresponds to operation 404 b ofFIG. 4A, a purge gas is flowed and no plasma is ignited. In RF phase416B, which corresponds to operation 406 b of FIG. 4A, the plasma isturned on and the second reactant is flowed. In purge phase 418B, whichcorresponds to operation 408 b of FIG. 4A, a purge gas is flowed and noplasma is ignited. FIG. 4B shows phases for repeating operations 402a-408 b of FIG. 4A, such that the second process cycle 490 includes thedose phase 412A with two carrier gas flows and precursor flow, purgephase 414A, RF phase 416A, purge phase 418A, then dose phase 412Binvolving one carrier gas flow with precursor flow, purge phase 414B, RFphase 416B, and purge phase 418B.

FIGS. 5A and 5B provide another example of a multi-cyclic ALD processwhere a parameter value is changed from cycle to cycle; in this example,the parameter is dose time during precursor exposure. As shown in FIG.5A, in operation 502 a, the substrate is exposed to a precursor at afirst dose time. The first dose time may be between about 50 ms to about100 ms. In operation 504 a, the chamber is optionally purged to removeany precursor molecules not adsorbed to the surface of the substrate.The purge may have any of the parameter values described above withrespect to operation 504 a of FIG. 5A.

In operation 506 a, the substrate is exposed to a plasma. During thisoperation, a second reactant flows to the substrate and the plasma isturned on to ignite the second reactant such that the second reactantreacts with the adsorbed precursor to form a film on the substrate.Process conditions may be any of those described above with respect tooperation 406 a of FIG. 4A.

In operation 508 a, the chamber is again optionally purged. The purgeconditions may be any of those described above with respect to operation404 a of FIG. 4A.

Operations 502 a-508 a may constitute one ALD cycle of a multi-cyclicALD process. In operation 502 b, the substrate is exposed to a precursorat a second dose time. The second dose time may be greater than or lessthan the dose time of operation 502 a. In some embodiments, the first orsecond dose time may be at least about 0.05 second. In certainembodiments, the difference between the first, second and subsequentdose times is about 0.025 second or longer. For example, if the dosetime of operation 502 a is about 0.1 seconds, the dose time of operation502 b may be about 0.125 seconds or higher. The dose time may beselected depending on the desired deposition result. For example, inoperation 502 a, the dose time may be about 0.1 seconds, which causesprecursor to be preferentially adsorbed toward the center of the waferdue to showerhead and chamber design. In operation 502 b, the dose timemay then be about 0.3 seconds to saturate precursor adsorption in thecenter and increase precursor on the edges of the substrate to moreuniformly deposit a film on the substrate. In operation 504 b, thechamber is optionally purged, which may involve any conditions describedabove with respect to operation 404 a in FIG. 4A. In operation 506 b,the substrate is exposed to a plasma. In operation 508 b, the chamber isagain optionally purged. Operations 502 a-508 b may constitute onemulti-cyclic ALD process including two ALD cycles with a variedparameter being dose time during precursor exposure and these operationsmay be repeated in cycles. The process does not need to unfold withcycle “a” and cycle “b” being paired at all points in the ALD process.For example, the “b” cycle may be performed once for every two or more“a” cycles. Or the “b” cycle may be performed irregularly or evenrandomly as determined before deposition or during deposition, throughreal-time feedback on the process.

For dose time variation, in some embodiments, dose time depends on thetype of pattern on the substrate. For example, trenches may be fairlydeep with high aspect ratio e.g. trenches can be as deep as 2-5 μm withtrench opening between about 0.1 and about 0.5 μm. The dose time may belonger to allow diffusion into the trenches, for example greater thanabout 0.2 second. Using shorter dose times for such trenches in amulti-cyclic ALD process e.g. about 0.1 second, the material mayprimarily grow toward the top or opening of the trench or feature, whichmay result in voids in the trench. Longer dose time may yield aconformal film along the trench wall whereas shorter dose time mayincrease film growth at or near the top of a trench. Multi-cyclic ALDcan use such variation to create a controlled air gap or void desirablefor certain applications.

FIG. 5B shows an example of a process 500 whereby operations 502 a-508 bin FIG. 5A are repeated in cycles.

As shown, the first process cycle 580 includes both the first ALD cycle510A (which correspond to operations 502 a-508 a) and second ALD cycle510B (which correspond to operations 502 b-508 b). The first ALD cycle510A involves a dose phase 512A corresponding to operation 502 a of FIG.5A whereby a carrier gas is flowed, a precursor is flowed, no plasma isflowed, and no second reactant is flowed. Note the length of the dose isrepresented by the length of the horizontal line corresponding to theprecursor exposure, or the x-axis of the precursor schematic. Purgephase 514A includes only purge gas flow and corresponds to operation 504a of FIG. 5A. The RF phase 516A corresponds to operation 506 a of FIG.5A, whereby the second reactant is flowed and the plasma is turned on.Purge phase 518A corresponds to operation 508A, and only the purge gasis flowed. The carrier gas is flowed whenever precursor gas is flowed;e.g., at every dose phase. Here, the carrier gas flow represents thecarrier gas used to carry the precursor gas into the chamber and ispulsed into the chamber where a substrate is housed.

In the second ALD cycle 510B, the dose phase 512B corresponds tooperation 504 b of FIG. 5A. During the dose phase 512B, the carrier isflowed with a precursor for a dose time longer than that of dose phase512A. Note that in some embodiments, the reverse may be true—dose phase512B may be shorter than that of dose phase 512A. Purge phase 514B maycorrespond to operation 504 b of FIG. 5A. During purge phase 514B, onlycarrier gas is flowed, and precursor flow and second reactant flow areturned off, as is the plasma. In RF phase 516B, which corresponds tooperation 506 b of FIG. 5A, the second reactant is flowed and the plasmais turned on. Purge phase 518B corresponds to operation 508 b, andduring purge phase 518B, only the purge gas is flowed.

The first process cycle 580 is repeated in the example provided in FIG.5B as shown in second process cycle 590. Second process cycle 590includes a first ALD cycle 550A, corresponding to repeating operations502 a-508 a of FIG. 5A. First ALD cycle 550A includes the sameoperations as first ALD cycle 510A, such that there is a dose phase552A, purge phase 554A, RF phase 556A, and purge phase 558A. Theseoperations are the same as dose phase 512A, purge phase 514A, RF phase516A, and purge phase 518A, respectively. The dose time of 552A is thesame as that of dose time 512A.

A second ALD cycle 550B is performed, which includes the same operationsas second ALD cycle 510B. These operations correspond to operations 502b-508 b in FIG. 5A. Second ALD cycle 550B involves a dose phase 552B, apurge phase 554B, an RF phase 556B, and purge phase 558B. Thesecorrespond to dose phase 512B, purge phase 514B, RF phase 516B, andpurge phase 518B, respectively. The duration of dose phase 552B is thesame as that of dose phase 512B. As described above for first processcycle 580, the dose phase 552B duration is longer than that of dosephase 552A, such that dose time is varied from ALD cycle to ALD cyclewithin one multi-cyclic ALD process cycle.

Although embodiments described herein involve exposing the substrate toa plasma during the second reactant exposure, disclosed embodiments mayalso be used for thermal processes. In some embodiments involvingthermal ALD, the gas is distributed through a tube to more uniformlydistribute gas to the chamber. In embodiments involving plasma-enhancedALD, the gas may be flowed through a showerhead as described below totailor the deposition profile. In some embodiments, only a singlereactant is used and a thermal or plasma operation is used to convertadsorbed precursor to a desired deposition material.

Apparatus

FIG. 6 depicts a schematic illustration of an embodiment of an atomiclayer deposition (ALD) process station 600 having a process chamber body602. The ALD process station 600 may be suitable for processingsubstrates in a low-pressure environment in some embodiments. In someembodiments, one or more hardware parameter values of ALD processstation 600, including those discussed in detail below may be adjustedprogrammatically by one or more computer controllers 650. In variousembodiments, parameter values of an ALD process are varied across cyclesin a multi-cyclic ALD process as described herein. Variation of theparameter values may be made in a determined manner or based onreal-time feedback. Additional examples and further embodiments aredescribed below.

ALD process station 600 fluidly communicates with reactant deliverysystem 601 a for delivering process gases to a distribution showerhead606. Reactant delivery system 601 a includes a mixing vessel 604 forblending and/or conditioning process gases for delivery to showerhead606. For example, the reactant delivery system 601 a may include massflow controllers and liquid flow controllers as described below. One ormore mixing vessel inlet valves 620 may control introduction of processgases to mixing vessel 604. In various embodiments, delivery of one ormore process gases to the showerhead 606 or to the process chamber 602may be varied across cycles. For example, the duration of dosing one ormore process gases may be varied. In disclosed embodiments, a controller650 may control the diversion of one or more process gases bycontrolling one or more inlet valves 620. Variation of gas delivery maybe made in a determined manner. For example, a recipe may be programmedto the controller 650 for diverting a first process gas every n cyclesof flowing a second process gas, where n is an integer greater than orequal to 1. In some embodiments, carrier gases delivered by reactantdelivery system 601 a may also be varied from cycle to cycle. Forexample, the dose duration may be varied across cycles. In someembodiments, variation of gas delivery may be based on real-timefeedback. For example, a detector (not shown) may determine how muchfilm was deposited on substrate 612 over time, and dose times of one ormore gases (such as process gases or carrier gases) may be varied acrosscycles in a multi-cyclic ALD process to accommodate the state ofsubstrate 612 at any given time.

As an example, the embodiment of FIG. 6 includes a vaporization point603 for vaporizing liquid reactant to be supplied to the mixing vessel604. In some embodiments, vaporization point 603 may be a heatedvaporizer. The saturated reactant vapor produced from such vaporizersmay condense in downstream delivery piping. Exposure of incompatiblegases to the condensed reactant may create small particles. These smallparticles may clog piping, impede valve operation, contaminatesubstrates, etc. Some approaches to addressing these issues involvepurging and/or evacuating the delivery piping to remove residualreactant. However, purging the delivery piping may increase processstation cycle time, degrading process station throughput. Thus, in someembodiments, delivery piping downstream of vaporization point 603 may beheat traced. In some examples, mixing vessel 604 may also be heattraced. In one non-limiting example, piping downstream of vaporizationpoint 603 has an increasing temperature profile extending fromapproximately 30° C. to approximately 150° C. at mixing vessel 604.

In some embodiments, liquid precursor or liquid reactant may bevaporized at a liquid injector. For example, a liquid injector mayinject pulses of a liquid reactant into a carrier gas stream upstream ofthe mixing vessel. In one embodiment, a liquid injector may vaporize thereactant by flashing the liquid from a higher pressure to a lowerpressure. In another example, a liquid injector may atomize the liquidinto dispersed microdroplets that are subsequently vaporized in a heateddelivery pipe. Smaller droplets may vaporize faster than largerdroplets, reducing a delay between liquid injection and completevaporization. Faster vaporization may reduce a length of pipingdownstream from vaporization point 603. In one scenario, a liquidinjector may be mounted directly to mixing vessel 604. In anotherscenario, a liquid injector may be mounted directly to showerhead 606.

In some embodiments, a liquid flow controller (LFC) upstream ofvaporization point 603 may be provided for controlling a mass flow ofliquid for vaporization and delivery to process station 600. Forexample, the LFC may include a thermal mass flow meter (MFM) locateddownstream of the LFC. A plunger valve of the LFC may then be adjustedresponsive to feedback control signals provided by aproportional-integral-derivative (PID) controller in electricalcommunication with the MFM. However, it may take one second or more tostabilize liquid flow using feedback control. This may extend a time fordosing a liquid reactant. Thus, in some embodiments, the LFC may bedynamically switched between a feedback control mode and a directcontrol mode. In some embodiments, this may be performed by disabling asense tube of the LFC and the PID controller.

Showerhead 606 distributes process gases toward substrate 612. In theembodiment shown in FIG. 6, the substrate 612 is located beneathshowerhead 606 and is shown resting on a pedestal 608. Showerhead 606may have any suitable shape, and may have any suitable number andarrangement of ports for distributing process gases to substrate 612.

In some embodiments, a microvolume 607 is located beneath showerhead606. Practicing disclosed embodiments in a microvolume rather than inthe entire volume of a process station may reduce reactant exposure andpurge times, may reduce times for altering process conditions (e.g.,pressure, temperature, etc.), and may limit an exposure of processstation robotics to process gases, etc. Example microvolume sizesinclude, but are not limited to, volumes between 0.1 liter and 2 liters.This also impacts productivity throughput. In some embodiments, thedisclosed embodiments are not performed in a microvolume.

In some embodiments, pedestal 608 may be raised or lowered to exposesubstrate 612 to microvolume 607 and/or to vary a volume of microvolume607. For example, in a substrate transfer phase, pedestal 608 may beraised to position substrate 612 within microvolume 607. In someembodiments, microvolume 607 may completely enclose substrate 612 aswell as a portion of pedestal 608 to create a region of high flowimpedance.

Optionally, pedestal 608 may be lowered and/or raised during portionsthe process to modulate process pressure, reactant concentration, etc.,within microvolume 607. In one scenario where process chamber body 602remains at a base pressure during the process, lowering pedestal 608 mayallow microvolume 607 to be evacuated. Example ratios of microvolume toprocess chamber volume include, but are not limited to, volume ratiosbetween 1:500 and 1:10. It will be appreciated that, in someembodiments, pedestal height may be adjusted programmatically by asuitable computer controller 650. In some embodiments, location of thepedestal 608 may be varied across cycles. For example, in some ALDcycles, the pedestal 608 may be raised, and in some ALD cycles, thepedestal 608 may be lowered. Variations as described herein may bedependent on real-time feedback or a determined recipe.

In another scenario, adjusting a height of pedestal 608 may allow aplasma density to be varied during plasma activation and/or depositioncycles included in disclosed multi-cyclic ALD processes. At theconclusion of the process phase, pedestal 608 may be lowered duringanother substrate transfer phase to allow removal of substrate 612 frompedestal 608.

While the example microvolume variations described herein refer to aheight-adjustable pedestal, it will be appreciated that, in someembodiments, a position of showerhead 606 may be adjusted relative topedestal 608 to vary a volume of microvolume 607. Further, it will beappreciated that a vertical position of pedestal 608 and/or showerhead606 may be varied by any suitable mechanism within the scope of thepresent disclosure. In some embodiments, pedestal 608 may include arotational axis for rotating an orientation of substrate 612. It will beappreciated that, in some embodiments, one or more of these exampleadjustments may be performed programmatically by one or more suitablecomputer controllers 650.

In some embodiments where plasma may be used as discussed above,showerhead 606 and pedestal 608 electrically communicate with a radiofrequency (RF) power supply 614 and matching network 616 for powering aplasma. In some embodiments, the plasma energy may be controlled bycontrolling one or more of a process station pressure, a gasconcentration, an RF source power, an RF source frequency, and a plasmapower pulse timing. Such parameter values may be varied from ALD cycleto ALD cycle in a multi-cyclic ALD process as described herein. Forexample, RF power supply 614 and matching network 616 may be operated atany suitable power to form a plasma having a desired composition ofradical species during one or more ALD cycles. Examples of suitablepowers are included above. Likewise, RF power supply 614 may provide RFpower of any suitable frequency. In some embodiments, RF power supply614 may be configured to control high- and low-frequency RF powersources independently of one another. Example low-frequency RFfrequencies may include, but are not limited to, frequencies between 50kHz and 500 kHz. Example high-frequency RF frequencies may include, butare not limited to, frequencies between 1.8 MHz and 2.45 GHz. It will beappreciated that any suitable parameter values may be modulateddiscretely or continuously to provide plasma energy for the surfacereactions. In one non-limiting example, the plasma power may beintermittently pulsed to reduce ion bombardment with the substratesurface relative to continuously powered plasmas. In some embodiments,the plasma power can be between about 50 W and about 6000 W.

In various embodiments, the RF power or RF frequency or both may bevaried across cycles. In some embodiments, the RF power in combinationwith one or more other parameter values of an ALD process may be variedfrom cycle to cycle, or every n cycles, or randomly. For example, insome embodiments, a high RF power may be used in one ALD cycle while alow RF power is used in the next ALD cycle, and so on. In someembodiments, more than two variations in RF power may be used in amulti-cyclic ALD process.

In some embodiments, the plasma may be monitored in-situ by one or moreplasma monitors. In one scenario, plasma power may be monitored by oneor more voltage, current sensors (e.g., VI probes). In another scenario,plasma density and/or process gas concentration may be measured by oneor more optical emission spectroscopy sensors (OES). In someembodiments, one or more plasma parameter values may be programmaticallyadjusted based on measurements from such in-situ plasma monitors. Forexample, an OES sensor may be used in a feedback loop for providingprogrammatic control of plasma power. It will be appreciated that, insome embodiments, other monitors may be used to monitor the plasma andother process characteristics. Such monitors may include, but are notlimited to, infrared (IR) monitors, acoustic monitors, and pressuretransducers.

In some embodiments, instructions for a controller 650 may be providedvia input/output control (IOC) sequencing instructions. In one example,the instructions for setting conditions for a process phase may beincluded in a corresponding recipe phase of a process recipe. In somecases, process recipe phases may be sequentially arranged, so that allinstructions for a process phase are executed concurrently with thatprocess phase. In some embodiments, instructions for setting one or morereactor parameter values may be included in a recipe phase. For example,a first recipe phase may include instructions for setting a flow rate ofan inert and/or a reactant gas (e.g., the first precursor such assilane), instructions for setting a flow rate of a carrier gas (such asnitrogen or argon), and time delay instructions for the first recipephase. A second, subsequent recipe phase may include instructions formodulating or stopping a flow rate of an inert and/or a reactant gas,and instructions for modulating a flow rate of a carrier or purge gasand time delay instructions for the second recipe phase. A third recipephase may include instructions for setting a flow rate of an inertand/or reactant gas which may be the same as or different from the gasused in the first recipe phase (e.g., the second precursor such asoxygen), instructions for setting a plasma RF power, instructions formodulating a flow rate of a carrier gas which may be the same as ordifferent from the flow rate in the first recipe phase, plasmaconditions, and time delay instructions for the third recipe phase. Afourth recipe phase may include instructions for modulating or stoppinga flow rate of an inert and/or a reactant gas, instructions formodulating the flow rate of a carrier or purge gas, and time delayinstructions for the fourth recipe phase. More recipe phases may also beused. For example, another recipe phase may include plasma conditionsdifferent from that of the third recipe phase for embodiments varyingplasma conditions from cycle to cycle, or every n cycles, or randomly,or dependent on real-time feedback. It will be appreciated that theserecipe phases may be further subdivided and/or iterated in any suitableway within the scope of the present disclosure.

In some embodiments, pedestal 608 may be temperature controlled viaheater 610. Further, in some embodiments, pressure control for processstation 600 may be provided by butterfly valve 618. As shown in theembodiment of FIG. 6, butterfly valve 618 throttles a vacuum provided bya downstream vacuum pump (not shown). However, in some embodiments,pressure control of process station 600 may also be adjusted by varyinga flow rate of one or more gases introduced to the process station 600.The process station 600 may include a control 650 for controllingexample recipes as described above.

In some implementations, a controller 650 is part of a system, which maybe part of the above-described examples. Such systems can comprisesemiconductor processing equipment, including a processing tool ortools, chamber or chambers, a platform or platforms for processing,and/or specific processing components (a wafer pedestal, a gas flowsystem, etc.). These systems may be integrated with electronics forcontrolling their operation before, during, and after processing of asemiconductor wafer or substrate. The electronics may be referred to asthe “controller,” which may control various components or subparts ofthe system or systems. The controller 650, depending on the processingrequirements and/or the type of system, may be programmed to control anyof the processes disclosed herein, including the delivery of processinggases and/or variation of different dose times for delivery of processgases including diversion of one or more gases, temperature settings(e.g., heating and/or cooling), pressure settings, vacuum settings,power settings, radio frequency (RF) generator settings and/or variationof RF power settings, RF matching circuit settings, frequency settings,flow rate settings, fluid delivery settings, positional and operationsettings, wafer transfers into and out of a tool and other transfertools and/or load locks connected to or interfaced with a specificsystem.

Broadly speaking, the controller 650 may be defined as electronicshaving various integrated circuits, logic, memory, and/or software thatreceive instructions, issue instructions, control operation, enablecleaning operations, enable endpoint measurements, and the like. Theintegrated circuits may include chips in the form of firmware that storeprogram instructions, digital signal processors (DSPs), chips defined asapplication specific integrated circuits (ASICs), and/or one or moremicroprocessors, or microcontrollers that execute program instructions(e.g., software). Program instructions may be instructions communicatedto the controller 650 in the form of various individual settings (orprogram files), defining operational parameters for carrying out aparticular process on or for a semiconductor wafer or to a system. Theoperational parameters may, in some embodiments, be part of a recipedefined by process engineers to accomplish one or more processing stepsduring the fabrication of one or more layers, materials, metals, oxides,silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.

The controller 650, in some implementations, may be a part of or coupledto a computer that is integrated with, coupled to the system, otherwisenetworked to the system, or a combination thereof. For example, thecontroller 650 may be in the “cloud” or all or a part of a fab hostcomputer system, which can allow for remote access of the waferprocessing. The computer may enable remote access to the system tomonitor current progress of fabrication operations, examine a history ofpast fabrication operations, examine trends or performance metrics froma plurality of fabrication operations, to change parameters of currentprocessing, to set processing steps to follow a current processing, orto start a new process. In some examples, a remote computer (e.g. aserver) can provide process recipes to a system over a network, whichmay include a local network or the Internet. The remote computer mayinclude a user interface that enables entry or programming of parametersand/or settings, which are then communicated to the system from theremote computer. In some examples, the controller 650 receivesinstructions in the form of data, which specify parameters for each ofthe processing steps to be performed during one or more operations. Itshould be understood that the parameters may be specific to the type ofprocess to be performed and the type of tool that the controller 650 isconfigured to interface with or control. Thus as described above, thecontroller 650 may be distributed, such as by including one or morediscrete controllers that are networked together and working towards acommon purpose, such as the processes and controls described herein. Anexample of a distributed controller for such purposes would be one ormore integrated circuits on a chamber in communication with one or moreintegrated circuits located remotely (such as at the platform level oras part of a remote computer) that combine to control a process on thechamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a chemical vapor deposition (CVD) chamber or module, anatomic layer deposition (ALD) chamber or module, an atomic layer etch(ALE) chamber or module, an ion implantation chamber or module, a trackchamber or module, and any other semiconductor processing systems thatmay be associated or used in the fabrication and/or manufacturing ofsemiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the controller 650 might communicate with one or more ofother tool circuits or modules, other tool components, cluster tools,other tool interfaces, adjacent tools, neighboring tools, tools locatedthroughout a factory, a main computer, another controller, or tools usedin material transport that bring containers of wafers to and from toollocations and/or load ports in a semiconductor manufacturing factory.

As described above, one or more process stations may be included in amulti-station processing tool. FIG. 7 shows a schematic view of anembodiment of a multi-station processing tool 700 with an inbound loadlock 702 and an outbound load lock 704, either or both of which maycomprise a remote plasma source. A robot 706, at atmospheric pressure,is configured to move wafers from a cassette loaded through a pod 708into inbound load lock 702 via an atmospheric port 710. A wafer isplaced by the robot 706 on a pedestal 712 in the inbound load lock 702,the atmospheric port 710 is closed, and the load lock is pumped down.Where the inbound load lock 702 comprises a remote plasma source, thewafer may be exposed to a remote plasma treatment in the load lock priorto being introduced into a processing chamber 714. Further, the waferalso may be heated in the inbound load lock 702 as well, for example, toremove moisture and adsorbed gases. Next, a chamber transport port 716to processing chamber 714 is opened, and another robot (not shown)places the wafer into the reactor on a pedestal of a first station shownin the reactor for processing. While the embodiment depicted in FIG. 7includes load locks, it will be appreciated that, in some embodiments,direct entry of a wafer into a process station may be provided.

The depicted processing chamber 714 comprises four process stations,numbered from 1 to 4 in the embodiment shown in FIG. 7. Each station hasa heated pedestal (shown at 718 for station 1), and gas line inlets. Itwill be appreciated that in some embodiments, each process station mayhave different or multiple purposes. For example, in some embodiments, aprocess station may be switchable between an ALD and plasma-enhanced ALDprocess mode. Additionally or alternatively, in some embodiments,processing chamber 714 may include one or more matched pairs of ALD andplasma-enhanced ALD process stations. While the depicted processingchamber 714 comprises four stations, it will be understood that aprocessing chamber according to the present disclosure may have anysuitable number of stations. For example, in some embodiments, aprocessing chamber may have five or more stations, while in otherembodiments a processing chamber may have three or fewer stations.

FIG. 7 depicts an embodiment of a wafer handling system 790 fortransferring wafers within processing chamber 714. In some embodiments,wafer handling system 790 may transfer wafers between various processstations and/or between a process station and a load lock. It will beappreciated that any suitable wafer handling system may be employed.Non-limiting examples include wafer carousels and wafer handling robots.FIG. 7 also depicts an embodiment of a system controller 750 employed tocontrol process conditions and hardware states of process tool 700.System controller 750 may include one or more memory devices 756, one ormore mass storage devices 754, and one or more processors 752. Processor752 may include a CPU or computer, analog and/or digital input/outputconnections, stepper motor controller boards, etc.

In some embodiments, system controller 750 controls all of theactivities of process tool 700. System controller 750 executes systemcontrol software 758 stored in mass storage device 754, loaded intomemory device 756, and executed on processor 752. Alternatively, thecontrol logic may be hard coded in the controller 750. ApplicationsSpecific Integrated Circuits, Programmable Logic Devices (e.g.,field-programmable gate arrays, or FPGAs) and the like may be used forthese purposes. In the following discussion, wherever “software” or“code” is used, functionally comparable hard coded logic may be used inits place. System control software 758 may include instructions forcontrolling the timing, mixture of gases, amount of sub-saturated gasflow, chamber and/or station pressure, chamber and/or stationtemperature, wafer temperature, target power levels, RF power levels,substrate pedestal, chuck and/or susceptor position, and otherparameters of a particular process performed by process tool 700. Systemcontrol software 758 may be configured in any suitable way. For example,various process tool component subroutines or control objects may bewritten to control operation of the process tool components used tocarry out various process tool processes. System control software 758may be coded in any suitable computer readable programming language.

In some embodiments, system control software 758 may includeinput/output control (IOC) sequencing instructions for controlling thevarious parameters described above. Other computer software and/orprograms stored on mass storage device 754 and/or memory device 756associated with system controller 750 may be employed in someembodiments. Examples of programs or sections of programs for thispurpose include a substrate positioning program, a process gas controlprogram, a pressure control program, a heater control program, and aplasma control program.

A substrate positioning program may include program code for processtool components that are used to load the substrate onto pedestal 718and to control the spacing between the substrate and other parts ofprocess tool 700.

A process gas control program may include code for controlling gascomposition (e.g., silane, nitrogen, and purge gases as describedherein) and flow rates and optionally for flowing gas into one or moreprocess stations prior to deposition in order to stabilize the pressurein the process station. For example, a process gas control program mayinclude code for changing duration of process gas doses across cycles ina multi-cyclic ALD process. A pressure control program may include codefor controlling the pressure in the process station by regulating, forexample, a throttle valve in the exhaust system of the process station,a gas flow into the process station, etc.

A heater control program may include code for controlling the current toa heating unit that is used to heat the substrate. Alternatively, theheater control program may control delivery of a heat transfer gas (suchas helium) to the substrate.

A plasma control program may include code for setting RF power levelsapplied to the process electrodes in one or more process stations inaccordance with the embodiments herein. For example, a plasma controlprogram may include code for varying RF power levels across cycles.

A pressure control program may include code for maintaining the pressurein the reaction chamber in accordance with the embodiments herein.

In some embodiments, there may be a user interface associated withsystem controller 750. The user interface may include a display screen,graphical software displays of the apparatus and/or process conditions,and user input devices such as pointing devices, keyboards, touchscreens, microphones, etc.

In some embodiments, parameter values adjusted by system controller 750may relate to process conditions. Non-limiting examples include processgas composition and flow rates and dose times, temperature, pressure,plasma conditions (such as RF power levels), and variation of one ormore parameter values across ALD cycles, etc. These parameter values maybe provided to the user in the form of a recipe, which may be enteredutilizing the user interface.

Signals for monitoring the process may be provided by analog and/ordigital input connections of system controller 750 from various processtool sensors. The signals for controlling the process may be output onthe analog and digital output connections of process tool 700.Non-limiting examples of process tool sensors that may be monitoredinclude mass flow controllers, pressure sensors (such as manometers),thermocouples, etc. Appropriately programmed feedback and controlalgorithms may be used with data from these sensors to maintain processconditions.

System controller 750 may provide program instructions for implementingthe above-described deposition processes. The program instructions maycontrol a variety of process parameters, such as DC power level, RF biaspower level, pressure, temperature, etc. The instructions may controlthe parameter values to operate in-situ deposition of film stacksaccording to various embodiments described herein.

The system controller 750 will typically include one or more memorydevices and one or more processors configured to execute theinstructions so that the apparatus will perform a method in accordancewith disclosed embodiments. Machine-readable media containinginstructions for controlling process operations in accordance withdisclosed embodiments may be coupled to the system controller. Thecontroller 750 may have any of the features described above with respectto FIG. 6.

An appropriate apparatus for performing the methods disclosed herein isfurther discussed and described in U.S. patent application Ser. No.13/084,399, filed Apr. 11, 2011, and titled “PLASMA ACTIVATED CONFORMALFILM DEPOSITION”; and Ser. No. 13/084,305, filed Apr. 11, 2011, andtitled “SILICON NITRIDE FILMS AND METHODS,” each of which isincorporated herein in its entireties.

The apparatus/process described herein may be used in conjunction withlithographic patterning tools or processes, for example, for thefabrication or manufacture of semiconductor devices, displays, LEDs,photovoltaic panels and the like. Typically, though not necessarily,such tools/processes will be used or conducted together in a commonfabrication facility. Lithographic patterning of a film typicallyincludes some or all of the following operations, each operation enabledwith a number of possible tools: (1) application of photoresist on aworkpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curingof photoresist using a hot plate or furnace or UV curing tool; (3)exposing the photoresist to visible or UV or x-ray light with a toolsuch as a wafer stepper; (4) developing the resist so as to selectivelyremove resist and thereby pattern it using a tool such as a wet bench;(5) transferring the resist pattern into an underlying film or workpieceby using a dry or plasma-assisted etching tool; and (6) removing theresist using a tool such as an RF or microwave plasma resist stripper.

EXPERIMENTAL Experiment 1

An experiment was conducted comparing deposition uniformity formulti-cyclic ALD processes performed in accordance with disclosedembodiments. The apparatus used included two manifolds—Manifold 1 andManifold 2. Manifold 1 delivered a carrier gas and may be diverted.Manifold 2 delivered a carrier gas along with a silicon-containing ALDprecursor. The flow from Manifold 1 merged with Manifold 2 prior todelivery to the showerhead and into the process chamber where asubstrate was housed. Five substrates were evaluated and underwentdifferent carrier gas flows. Processes were performed at 50° C.

The first substrate involved repeating the following ALD cycle:Precursor dose with 9.5 slm carrier gas flow for 0.2 seconds, purge,1000 W oxidizing plasma exposure, and purge.

The second substrate involved repeating the following ALD cycle:precursor dose with 6 slm carrier gas flow for 0.2 seconds, purge, 1000W oxidizing plasma exposure, and purge.

The third substrate involved repeating the following ALD cycle:precursor dose with 3.5 slm carrier gas flow for 0.2 seconds, purge,1000 W oxidizing plasma exposure, and purge.

The fourth substrate involved repeating the following multi-cyclic ALDprocess cycle: precursor dose with 6 slm carrier gas flow for 0.2seconds, purge, 1000 W oxidizing plasma exposure, purge, precursor dosewith 9.5 slm carrier gas flow for 0.2 seconds, purge, 1000 W oxidizingplasma exposure, purge.

The fifth substrate involved repeating the following multi-cyclic ALDprocess cycle: precursor dose with 3.5 slm carrier gas flow for 0.2seconds, purge, 1000 W oxidizing plasma exposure, purge, precursor dosewith 9.5 slm carrier gas flow for 0.2 seconds, purge, 1000 W oxidizingplasma exposure, purge.

The timing diagram in FIG. 8A shows the flows of carrier gas and RFpower. “RF ON” represents the timing for when the plasma was turned on.“Man 1” shows the timing when Manifold 1 was turned on. “Man 2” showsthe timing when Manifold 2 was turned on—note it was flowed twice asfrequently as Manifold 1. In the first, second, and third substrates,the timing corresponded to using Man 2 and RF ON (lower half of FIG.8A). In the fourth and fifth substrates, the first cycle included onlyManifold 2 carrier gas, while the second cycle included both Manifold 2and Manifold 1, and such cycles were repeated such that the combinationof the top and bottom halves of FIG. 8A were all conducted.

The thicknesses of material deposited on the substrates were determinedusing 49-point polar metrology, where thickness measurements were takenon various points (point 1 being the center, points 2-9 forming a firstring around point 1, points 10-25 forming a second ring around the firstring, and points 26-49 forming a third ring around the second ring,measured 3 mm from the edge of the wafer. Nonuniformity (NU %) wasevaluated as was the deposition rate from mean thickness.

The results for thickness are depicted in FIG. 8B and in Table 1 below.As shown in FIG. 8B, an edge thin profile for a single carrier gas isshown as the line labeled 3.5 slm, and an edge thick profile for asingle carrier gas is shown as the line labeled 9.5 slm.

TABLE 1 1000 W Carrier Gas Flow Variation in Multi-cyclic ALD Mean NU %Process RF Power Carrier Gas Flow Thickness (Å) (R/2) Single Carrier1000 W 9.5 slm 886 0.51 Gas ALD Single Carrier 1000 W   6 slm 895 0.76Gas ALD Single Carrier 1000 W 3.5 slm 901 0.87 Gas ALD Multi-cyclic 1000W 6 slm, 9.5 slm 887 0.62 ALD Multi-cyclic 1000 W 3.5 slm, 9.5 slm 8930.54 ALD

As shown, a multi-cyclic ALD process such as shown for the 6-9.5 slm and3.5-9.5 slm wafers exhibited better NU %. Deposition rate was greater,likely due to the lower carrier gas flow and higher precursor partialpressure. The multi-cyclic processes were able to achieve both edgethick and edge thin profiles as shown in FIG. 8B.

Experiment 2

An experiment was conducted comparing deposition uniformity formulti-cyclic ALD processes performed in accordance with disclosedembodiments. Three substrates were evaluated and underwent differentcarrier gas flows. Processes were performed at 200° C.

The first substrate involved repeating the following ALD cycle:precursor dose with 9.5 slm carrier gas flow for 0.2 seconds, purge,1500 W oxidizing plasma exposure, and purge.

The second substrate involved repeating the following multi-cyclic ALDprocess cycle: precursor dose with 6 slm carrier gas flow for 0.2seconds, purge, 1500 W oxidizing plasma exposure, purge, and precursordose with 9.5 slm carrier gas flow for 0.2 seconds, purge, 1500 Woxidizing plasma exposure, purge.

The third substrate involved repeating the following multi-cyclic ALDprocess cycle: precursor dose with 3.5 slm carrier gas flow for 0.2seconds, purge, 1500 W oxidizing plasma exposure, purge, and precursordose with 9.5 slm carrier gas flow for 0.2 seconds, purge, 1500 Woxidizing plasma exposure, purge.

The first substrate involved only one carrier gas flow (Manifold 2,referring to FIG. 8A for the timing diagram), while the second and thirdsubstrates each involved multi-cyclic ALD processes with two ALD cycleswith different carrier gas flows (varying between Manifold 2 only andboth Manifold 1 and 2, referring to FIG. 8A for the timing diagram).

The thicknesses of material deposited on the substrates were determinedusing 49-point polar metrology. Nonuniformity (NU %) was evaluated aswas the deposition rate (DepR) from mean thickness. The results forthickness are depicted in FIGS. 9A (thickness) and 9B (normalizedthickness) and in Table 2 below.

TABLE 2 1500 W Carrier Gas Flow Variation in Multi-cyclic ALD Mean NU %Process RF Power Carrier Gas Flow Thickness (Å) (R/2) Single Carrier1500 W 9.5 slm 539 2.10 Gas ALD Multi-cyclic 1500 W 6 slm, 9.5 slm 5541.86 ALD Multi-cyclic 1500 W 3.5 slm, 9.5 slm 584 1.84 ALD

As shown, a multi-cyclic ALD process such as shown for the 3.5-9.5 slmand the 6-9.5 slm wafers exhibited better NU %. Deposition rate wasgreater, likely due to the lower carrier gas flow and resulting higherprecursor partial pressure. Both FIGS. 9A and 9B show the improveduniformity in the multi-cyclic ALD processes.

Experiment 3

An experiment was conducted comparing deposition uniformity formulti-cyclic ALD processes performed in accordance with disclosedembodiments. Five substrates were evaluated and underwent differentcarrier gas flows. Processes were performed at 200° C.

The first substrate involved repeating the following ALD cycle:precursor dose with 9.5 slm carrier gas flow for 0.2 seconds, purge,2500 W oxidizing plasma exposure, and purge.

The second substrate involved repeating the following ALD cycle:precursor dose with 6 slm carrier gas flow for 0.2 seconds, purge, 2500W oxidizing plasma exposure, and purge.

The third substrate involved repeating the following ALD cycle:precursor dose with 3.5 slm carrier gas flow for 0.2 seconds, purge,2500 W oxidizing plasma exposure, and purge.

The fourth substrate involved repeating the following multi-cyclic ALDprocess cycle: precursor dose with 6 slm carrier gas flow for 0.2seconds, purge, 2500 W oxidizing plasma exposure, purge, and precursordose with 9.5 slm carrier gas flow for 0.2 seconds, purge, 2500 Woxidizing plasma exposure, purge.

The fifth substrate involved repeating the following multi-cyclic ALDprocess cycle: precursor dose with 3.5 slm carrier gas flow for 0.2seconds, purge, 2500 W oxidizing plasma exposure, purge, and precursordose with 9.5 slm carrier gas flow for 0.2 seconds, purge, 2500 Woxidizing plasma exposure, purge.

Like Experiment 1, the first, second, and third substrates used onlyManifold 2. The fourth and fifth substrates varied between usingManifold 2 and using both Manifold 1 and 2 between cycles.

The thicknesses of material deposited on the substrates were determinedusing 49-point polar metrology. Nonuniformity (NU %) was evaluated aswas the deposition rate (DepR) from mean thickness. The results forthickness are depicted in FIGS. 10A (thickness) and 10B (normalizedthickness) and in Table 3 below.

TABLE 3 2500 W Carrier Gas Flow Variation in Multi-cyclic ALD Mean NU %Process RF Power Carrier Gas Flow Thickness (Å) (R/2) Single Carrier2500 W 9.5 slm 526 1.46 Gas ALD Single Carrier 2500 W   6 slm 553 1.40Gas ALD Single Carrier 2500 W 3.5 slm 585 1.47 Gas ALD Multi-cyclic 2500W 6 slm, 3.5 slm 538 1.30 ALD Multi-cyclic 2500 W 3.5 slm, 6 slm 5631.46 ALD

As shown, a multi-cyclic ALD process such as shown for the multi-cyclicALD wafers exhibited better NU %. Deposition rate was correlated tocarrier gas flow; lower carrier gas flow gave higher deposition rate.Both FIGS. 10A and 10B show the improved uniformity in the multi-cyclicALD processes.

Experiment 4

An experiment was conducted regarding deposition uniformity formulti-cyclic ALD processes performed in accordance with disclosedembodiments. Two substrates were exposed to single cycle ALD processes.Two substrates were exposed to multi-cyclic ALD processes with varyingdose times with 1000 W plasma power. Processes were performed at 50° C.

The first substrate involved repeating the following ALD cycle:precursor dose for 0.2 seconds, purge, 1000 W oxidizing plasma exposure,and purge.

The second substrate involved repeating the following ALD cycle:precursor dose for 0.1 seconds, purge, 1000 W oxidizing plasma exposure,and purge.

The third substrate involved repeating the following multi-cyclic ALDprocess cycle: precursor dose for 0.1 seconds, purge, 1000 W oxidizingplasma exposure, purge, precursor dose for 0.2 seconds, purge, 1000 Woxidizing plasma exposure, and purge.

The fourth substrate involved repeating the following multi-cyclic ALDprocess cycle: precursor dose for 0.2 seconds, purge, 1000 W oxidizingplasma exposure, purge, precursor dose for 0.3 seconds, purge, 1000 Woxidizing plasma exposure, and purge.

FIG. 11 shows an example of the dose time timing for a multi-cyclic ALDcycle used in this experiment. Note that the RF on duration is the sameevery cycle, whereas the dose time duration varies between long dosetime and short dose time.

The thicknesses of material deposited on the substrates were determinedusing 49-point polar metrology. Nonuniformity (NU %) was evaluated aswas the mean thickness. The results for thickness are depicted in FIG.12 and in Table 4 below.

TABLE 4 Dose Time Variation in Multi-cyclic ALD at 1000 W and 50° C.Mean NU % Process Dose Time Thickness (Å) (R/2) Single Cycle ALD 0.2 sec886 0.51 Single Cycle ALD 0.1 sec 847 0.74 Multi-cyclic ALD 0.1 sec, 0.2sec 865 0.63 Multi-cyclic ALD 0.2 sec, 0.3 sec 894 0.51

The results show an improvement in uniformity with increase in averagedose time e.g. 0.1 s dose time showed 0.74% NU whereas 0.15 s dose time(average of 0.1 and 0.2 s) showed a NU % of 0.63. It also shows that NU% stabilizes around average dose time of 0.2 s. FIG. 12 shows thicknessprofile of difference processes. The thickness at the edge relative tocenter decreases with increased dose time. These results suggest thatmulti-cyclic ALD can be used to tune the thickness profile.

CONCLUSION

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, it will be apparent thatcertain changes and modifications may be practiced within the scope ofthe appended claims. It should be noted that there are many alternativeways of implementing the processes, systems, and apparatus of thepresent embodiments. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the embodiments arenot to be limited to the details given herein.

The invention claimed is:
 1. A method of processing a substrate housedin a chamber, the method comprising: (a) exposing the substrate to areactant for a duration insufficient to saturate the surface of thesubstrate, wherein exposing the substrate to the reactant furthercomprises flowing one or more carrier gases; (b) exposing the substrateto a plasma to deposit at least a partial layer of film on thesubstrate; and (c) repeating (a) and (b) in two or more depositioncycles in alternating pulses, wherein the carrier gas flow rates of atleast one of the one or more carrier gases during (a) are varied duringthe two or more deposition cycles from deposition cycle to depositioncycle.
 2. The method of claim 19, wherein one of the one or moreparameters is the duration of (a).
 3. The method of claim 19, whereinone of the one or more parameters is a duration of (b).
 4. The method ofclaim 19, wherein the duration of (a) is greater than a duration of (b).5. (canceled)
 6. The method of claim 1, wherein exposing the substrateto the plasma further comprises flowing a process gas, and whereinprocess gas flow rate during (b) is varied during the two or moredeposition cycles from deposition cycle to deposition cycle.
 7. Themethod of claim 19, wherein one of the one or more parameters is plasmapower during (b).
 8. The method of claim 19, wherein one of the one ormore parameters is composition of the reactant in (a).
 9. The method ofclaim 1, wherein composition of the one or more carrier gases flowedduring (a) is varied during the two or more deposition cycles fromdeposition cycle to deposition cycle.
 10. The method of claim 1, whereinexposing the substrate to the plasma further comprises flowing one ormore process gases, and wherein composition of the one or more processgases flowed during (b) is varied during the two or more depositioncycles from deposition cycle to deposition cycle.
 11. The method ofclaim 1, wherein exposing the substrate to the plasma in (b) furthercomprises exposing the substrate to a second reactant.
 12. The method ofclaim 1, further comprising (d) purging the chamber after at least oneof (a) or (b) during one or more of the two or more deposition cycles.13. The method of claim 12, wherein purging the chamber comprisesflowing a purge gas.
 14. The method of claim 12, wherein duration of (d)is varied during the two or more deposition cycles from deposition cycleto deposition cycle.
 15. The method of claim 12, wherein composition ofthe purge gas in (d) is varied during the two or more deposition cyclesfrom deposition cycle to deposition cycle.
 16. The method of claim 11,wherein composition of the second reactant is varied during the two ormore deposition cycles from deposition cycle to deposition cycle. 17.The method of claim 2, wherein the duration of (a) is between about 0.05seconds and about 5 seconds.
 18. The method of claim 1, wherein plasmapower during (b) is between about 50 W and about 6000 W.
 19. The methodof claim 1, further comprising varying one or more parameters during atleast one of (a) or (b) during the two or more deposition cycles fromdeposition cycle to deposition cycle.
 20. A method of processing asubstrate housed in a chamber, the method comprising: (a) exposing thesubstrate to a reactant for a duration insufficient to saturate thesurface of the substrate; (b) exposing the substrate to a plasma todeposit at least a partial layer of film on the substrate; and (c)repeating (a) and (b) in two or more deposition cycles in alternatingpulses, wherein the plasma power during (b) is varied during the two ormore deposition cycles from deposition cycle to deposition cycle.